Lymphatics Flashcards
What are the functions of the lymphatic system?
Regulate volume of interstitial fluid, transport chylomicrons to the blood, carry material to local lymph nodes to prime the body’s immune response.
What is the difference between oedema and lymphoedema?
Oedema is swelling caused by an increased rate of diffusion of fluid from the capillaries, so the lymphatic vessels can’t absorb enough fluid to balance it, e.g from inflammation, malnutrition causing a decrease in blood proteins, hypertension.
Lymphoedema is swelling caused by a problem with the lymphatic vessels so they don’t drain the interstitial fluid as effectively, e.g primary lymphoedema with faulty valves in the lymphatic vessels, secondary lymph oedema caused by removal of lymph nodes.
What is the name for disorders of the bone marrow that cause an overproduction of blood cells, and give some examples.
Myeloproliferative neoplasms.
E.g polycythaemia vera (excess RBCs), essential thrombocythaemia (excess platelets), idiopathic myelofibrosis (too few RBCs, too many platelets and leukocytes).
Which vessel does the right lymphatic duct empty into and what region does it drain?
Empties into the right brachiocephalic vein; drains the right side of the head, the right shoulder, the right arm and the right side of the thorax.
Which vessel does the thoracic duct empty into and what region does it drain?
Left brachiocephalic vein; and drains the left side of the head and thorax, the left arm, and all the lower body.
What do the haematopoietic stem cells do as they differentiate and follow different lineages depending on their gene expression?
Make fate choices.
Which primary lymphatic tissues do the B lymphocytes and T lymphocytes each mature in?
B lymphocytes = another haematopoietic niche in the bone marrow.
T lymphocytes = thymus (maturing from the darkly staining cortex to the lightly staining medulla).
What is MALT?
Mucosal associated lymphoid tissue e.g Peyer’s patches.
They are lymphatic nodules which are aggregates of lymphocytes in a reticular mesh.
What is the key word to do with the organisation of immune tissues?
Compartmentalisation.
Why is the lymphatic system pressure dependant?
It doesn’t have a pump like the heart.
How does the wall of blind ending lymphatic vessels allow fluid to enter down a pressure gradient?
It is constructed of overlapping endothelial cells which respond to pressure and allow fluid to flow in through the flaps.
Name the major groups of lymph nodes.
Cervical lymph nodes, axillary lymph nodes, bronco-mediastinal lymph nodes, pre-aortic lymph nodes, para-aortic lymph nodes, deep inguinal lymph nodes.
Why is a lymph node a confluence of the two circulatory systems?
It has blood vessels as well as lymph vessels.
Which way do cells move through a lymph node when an immune response is generated?
Lymphocytes move out of the blood vessels into the lymph node, then leave in the efferent lymph vessel and are emptied into the blood circulation again and transported to the site of infection.
What are the cells called which provide the structural compartmentalisation of lymphatic tissue, and also a scaffold to allow cells to move between compartments?
Stromal cells.
